The number of connection terminals in a semiconductor device (an LSI: a large scale integrated circuit) has tended to increase in recent years along with advances in performance and integration of such a semiconductor device, and there is a growing demand for further reduction in size of connection terminals.
In flip-chip mounting, a connection terminal of a semiconductor device and a connection terminal of a wiring board are connected to each other by using a solder bump. Such a solder bump is made of an alloy (solder) such as Sn-3.5 wt % Ag, Sn-0.7 wt % Cu or Sn-3 wt % Ag-0.5 wt % Cu. In the meantime, the connection terminals of the semiconductor device and the wiring board are usually made of Cu (copper). Surfaces of the connection terminals may occasionally be plated with Ni (nickel) or Au (gold) in order to prevent corrosion or to improve solder wettability on the surfaces of the terminals.
[Patent Document 1] Japanese Laid-open Patent Publication No. 10-41621